Diagnostic difficulties in pernicious anemia.

Pernicious anemia (PA), the commonest cause of cobalamin deficiency (CD) in the world, is an autoimmune disease of multifactorial origin and is characterized by chronic atrophic gastritis (CAG) and defective absorption of cobalamin from the terminal ileum due to interference by the intrinsic factor (IF) antibodies. PA-related CD is a lengthy process, which if untreated, can lead to irreversible hematological and neurological sequelae. Although safe and effective therapy is available and the management of PA is straightforward, the diagnosis of PA can be extremely difficult to obtain due to myriad and diverse clinical presentations, frequently coexisting diseases, and limitations of currently available diagnostic tests. Diagnostic dilemmas may occur when PA patients present with normal or spuriously high serum cobalamin levels, dysplastic features of ring sideroblasts in the bone marrow (BM), hemolysis, and concomitant diseases such as iron deficiency or thalassemia. Herein, the author discusses an overview of diagnostic difficulties, with regards to morphological mimics, coexisting diseases, limitations of currently available tests, and how to diagnose PA in the era of imperfect laboratory tests.